function varargout = attributes(varargin)
% XMLTREE/ATTRIBUTES Method (handle attributes of an element node)
% FORMAT varargout = attributes(varargin)
% 
% tree    - XMLTree object
% method  - 'set','get','add','del' or 'length'
% uid     - the UID of an element node
% n       - indice of the attribute
% key     - string key="..."
% val     - string ...="val"
% attr    - cell array of struct(key,val) or just struct(key,val)
% l       - number of attributes of the element node uid
%
%     tree = attributes(tree,'set',uid,n,key,val)
% 	  attr = attributes(tree,'get',uid[,n])
% 	  tree = attributes(tree,'add',uid,key,val)
% 	  tree = attributes(tree,'del',uid[,n])
% 	  l    = attributes(tree,'length',uid)
%_______________________________________________________________________
%
% Handle attributes of an element node.
% The tree parameter must be in input AND in output for 'set', 'add' and
% 'del' methods.
%_______________________________________________________________________
% @(#)attributes.m               Guillaume Flandin             02/04/05

error(nargchk(3,6,nargin));
tree = varargin{1};
if ~ischar(varargin{2}) | ...
   ~any(strcmp(varargin{2},{'set','get','add','del','length'}))
	error('[XMLTree] Unknown method.');
end
uid = varargin{3};
if ~isa(uid,'double') | any(uid>length(tree)) | any(uid<1)
	error('[XMLTree] UID must be a positive integer scalar.');
end

if ~strcmp(tree.tree{uid}.type,'element')
	error('[XMLTree] This node has no attributes.');
end

switch varargin{2}
	case 'set'
		error(nargchk(6,6,nargin));
		if ~isa(varargin{4},'double') | ...
		   any(varargin{4}>length(tree.tree{uid}.attributes)) | ...
		   any(varargin{4}<1)
			error('[XMLTree] Invalid attribute indice.');
		end
		ind = varargin{4};
		tree.tree{uid}.attributes{ind} = struct('key',varargin{5},'val',varargin{6});
		varargout{1} = tree;
	case 'get'
		error(nargchk(3,4,nargin));
		if nargin == 4
			if ~isa(varargin{4},'double') | ...
			   any(varargin{4}>length(tree.tree{uid}.attributes)) | ...
			   any(varargin{4}<1)
				error('[XMLTree] Invalid attribute indice.');
			end
			if length(varargin{4}) == 1
				varargout{1} = tree.tree{uid}.attributes{varargin{4}(1)};
			else
				varargout{1} = {};
				for i=1:length(varargin{4})
					varargout{1}{i} = tree.tree{uid}.attributes{varargin{4}(i)};
				end
			end
		else
			if length(tree.tree{uid}.attributes) == 1
				varargout{1} = tree.tree{uid}.attributes{1};
			else
				varargout{1} = {};
				for i=1:length(tree.tree{uid}.attributes)
					varargout{1}{i} = tree.tree{uid}.attributes{i};
				end
			end
		end
	case 'add'
		error(nargchk(5,5,nargin));
		ind = length(tree.tree{uid}.attributes) + 1;
		tree.tree{uid}.attributes{ind} = struct('key',varargin{4},'val',varargin{5});
		varargout{1} = tree;
	case 'del'
		error(nargchk(3,4,nargin));
		if nargin == 4
			if ~isa(varargin{4},'double') | ...
		      any(varargin{4}>length(tree.tree{uid}.attributes)) | ...
		      any(varargin{4}<1)
				error('[XMLTree] Invalid attribute indice.');
			end
			ind = varargin{4};
			tree.tree{uid}.attributes(ind) = [];
		else
			tree.tree{uid}.attributes = [];
		end
		varargout{1} = tree;
	case 'length'
		error(nargchk(3,3,nargin));
		varargout{1} = length(tree.tree{uid}.attributes);
	otherwise
		error('[XMLTree] Unknown method.');
end
